Toola was the first rescued sea otter to ever rear pups that were successfully released to the wild.

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Toola swims at the Monterey Bay Aquarium on June 15, 2010. Toola died on March 3, 2012 at the age of 15 or 16 after suffering from a seizure disorder.

A sea otter that some are calling the most important animal in Monterey Bay Aquarium history died early this morning, according to aquarium representatives.

Toola, a sea otter rescued by the aquarium from Pismo Beach in 2001, was the first rescued sea otter to ever rear pups that were successfully released to the wild, according to the aquarium.

She died this morning at the age of 15 or 16 in the aquarium's veterinary care center from natural causes, aquarium staff said.

The longtime aquarium resident suffered from a seizure disorder that veterinarians believe stemmed from a brain infection known as toxoplasma gondii.

Southern California Animals in the News

Despite her illness, the pioneering sea otter was a surrogate mother to 13 rescued pups over the years.

At least five of those otters are still alive, and many have given birth to pups of their own, the aquarium found.

She also inspired former state Assemblyman and current state Insurance Commissioner Dave Jones to draft a bill to better safeguard the state's threatened sea otter population, according to aquarium staff.

"Toola was without question the most important animal in the history of our program," said Andrew Johnson, who manages the aquarium's Sea Otter Research and Conservation program, in a statement. "She showed us that captive otters could successfully raise orphaned pups for return to the wild. She inspired a critical piece of legislation that is helping protect sea otters. And she inspired millions of visitors to care more about sea otters. We will miss her."

Although she lived at the aquarium for more than a decade, Toola's caretakers say the sea otter remained a wild animal at heart.

"It was clear to everyone on the sea otter exhibit team that Toola, not me, was really in charge," said the aquarium's Associate Curator of Mammals, Christina DeAngelo, in a statement. "When she wanted to work on something in a training session she'd give me a 'look' or vocalize and I'd immediately cave in and do whatever she wanted."

Toola was one of roughly 600 ill and injured sea otters the aquarium has rescued under its Sea Otter Research and Conservation program -- which aims to study and save threatened sea otters -- since 1984.